Thermal imaging cameras are used in a variety of situations. For example, thermal imaging cameras are often used during maintenance inspections to thermally inspect equipment. Example equipment may include rotating machinery, electrical panels, or rows of circuit breakers, among other types of equipment. Thermal inspections can detect equipment hot spots such as overheating machinery or electrical components, helping to ensure timely repair or replacement of the overheating equipment before a more significant problem develops.
Thermal imaging cameras typically generate thermal images by capturing infrared energy emitted by an object and then translating the captured infrared energy into an image representative of a temperature profile across the object. Depending on the configuration of the camera, the thermal imaging camera may also generate a visible light image of the same object. The camera may display the infrared image and the visible light image in a coordinated manner, for example, to help an operator focus and interpret the thermal image generated by the thermal imaging camera. Unlike visible light images which generally provide good contrast between different objects, it is often difficult to recognize and distinguish different features in a thermal image as compared to the real-world scene. For this reason, an operator may rely on a visible light image to help interpret and focus the thermal image.
In applications where a thermal imaging camera is configured to generate both a thermal image and a visual light image, the camera may include two separate sets of optics for focusing the thermal image and visual light image. While the separate sets of optics can provide independent focusing control, the different positional arrangement of each set of optics can create a parallax, or shift, between the two images. The parallax may be proportional to the distance between each set of optics. The parallax may also be proportional to the distance between the thermal imaging camera and the object being observed. Accordingly, being able to accurately determine the distance between the thermal imaging camera and the object being observed during operation may be useful to resolve the parallax between the two images. Knowledge of the distance between a thermal imaging camera and an object being observed can be used for other purposes as well.